The cyber army of hackers supporting WikiLeaks has set its sites on the British government. The group is threatening to attack certain government websites if British police extradite WikiLeaks founder Julian Assange to Sweden where he is wanted for alleged sexual assault.

The loose association of hackers, which calls itself Anonymous, has this week already crashed the websites MasterCard, Visa, and the Swedish government by flooding their websites with millions of fake visitors. MasterCard and Visa drew Anonymous's wrath for refusing to continue processing payments for WikiLeaks donations.

It remains unclear what British government websites might come under attack. Gregg Housh, the unofficial spokesman for Anonymous, told The Daily Telegraph that Anonymous “will go after the weakest links, because they want to see results. They will probably test a few sites and then decide.”

The group is likely to be more selective in choosing its targets after its assault on Amazon failed. The Financial Times reports that Anonymous was “frustrated in their attempts to take down Amazon’s site, in spite of threatening the online retailer with a so-called ‘denial of service attack.’ "

The movement of hackers appears to be operating autonomously without any official links to WikiLeaks. Kristinn Hrafnsson, a spokesperson for the secret-spilling site, described the hackers’ actions as a “reflection of public opinion on the actions of the targets.” Reuters reports that she said Anonymous, which organizes on social networking sites and appears to operate without central leadership, “is not affiliated with WikiLeaks. There has been no contact between any WikiLeaks staffer and anyone at Anonymous.”

The group of hackers relies solely on volunteers to carry out its attacks. Rather than hijacking people’s computers, as is common in denial of service attacks, Anonymous relies on volunteers. As of Thursday night, about 31,000 people had downloaded special software that would allow their computers to be used in Anonymous attacks, reports The Independent.

Dutch police have arrested a teenager who prosecutors say has confessed to involvement in attacks against PayPal and MasterCard. The boy, who authorities have not yet named, is set to stand trial Friday, reports CNet News. Dutch law enforcement officials also confiscated computer equipment and say they are investigating the larger group of hackers.

Meanwhile, Assange and WikiLeaks have enjoyed an outpouring of offline support as well. In Australia, Assange’s homeland, hundreds of protesters rallied in three cities on Friday to protest his arrest by British authorities, reports ABC News.

Speaking at a rally in Brisbane, one protester said, “I'm speaking here today as a survivor of sexual abuse and I know what it is to not be listened to and not be believed. And I am standing here today and I am saying, free Julian Assange. Feminists for free speech are saying, loud and clear, they will not use our struggle against sexual assault in their struggle against freedom of speech.”